A plurality of standby paths may be set for an active path in order to enhance reliability of optical communication in an optical network. An “active path” and a “standby path” may be referred to as a “work path” and a “protection path,” respectively.
When a failure occurs in communication via an active path, the active path may be switched to any of the standby paths so as to relieve the communication via an active path with the standby path.
Related techniques are disclosed in, for example, Japanese Laid-Open Patent Publication No. 2011-160146 and Japanese Laid-Open Patent Publication No. 2011-130078.